M50LPW041K datasheet(16/37 Pages) STMICROELECTRONICS

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M50LPW041

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See Table 16 for details on the bit definitions of the

Lock Registers.

Write Lock. The

Write

Lock

Bit

determines

whether the contents of the Block can be modified

(using the Program or Block Erase Command).

When the Write Lock Bit is set, ‘1’, the block is

write protected; any operations that attempt to

change the data in the block will fail and the Status

Bit is reset, ‘0’, the block is not write protected

through the Lock Register and may be modified

unless write protected through some other means.

If Top Block Lock, TBL, is Low, VIL, then the Top

Block (Block 7) is write protected and cannot be

modified. Similarly, if Write Protect, WP, is Low,

VIL, then the Main Blocks (Blocks 0 to 6) are write

protected and cannot be modified.

After power-up or reset the Write Lock Bit is al-

ways set to ‘1’ (write protected).

Read Lock. The

Read

Lock

bit

determines

whether the contents of the Block can be read

(from Read mode). When the Read Lock Bit is set,

‘1’, the block is read protected; any operation that

attempts to read the contents of the block will read

00h instead. When the Read Lock Bit is reset, ‘0’,

read operations in the Block return the data pro-

grammed into the block as expected.

After power-up or reset the Read Lock Bit is al-

ways reset to ‘0’ (not read protected).

Lock Down. The Lock Down Bit provides a

mechanism for protecting software data from sim-

ple hacking and malicious attack. When the Lock

Down Bit is set, ‘1’, further modification to the

Write Lock, Read Lock and Lock Down Bits cannot

be performed. A reset or power-up is required be-

fore changes to these bits can be made. When the

Lock Down Bit is reset, ‘0’, the Write Lock, Read

Lock and Lock Down Bits can be changed.

General Purpose Input Register

The General Purpose Input Register holds the

state of the General Purpose Input pins, GPI0-

GPI4. When this register is read, the state of these

pins is returned. This register is read-only and writ-

ing to it has no effect.

The signals on the General Purpose Input pins

should remain constant throughout the whole Bus

Read cycle in order to guarantee that the correct

data is read.

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